Olefins, such as ethylene, are polymerized using as a polymerization catalyst selected transition metal complexes of anionic ligands having three donor atoms that may coordinate to the transition metal.
Polymers of olefins are important items of commerce, and these polymers are used in a myriad of ways, from low molecular weight polyolefins being used in lubricants and waxes, to higher molecular weight grades being used for fiber, films, molding resins, elastomers, etc.
Olefins may be polymerized by a variety of transition metal containing catalysts, for example metallocene and Ziegler-Natta type catalysts. More recently, other types of transition metal containing polymerization catalysts have been discovered, in which the transition metal atom is complexed to a neutral or monoanionic ligand. See, for instance, U.S. Pat. Nos. 5,714,556, 5,880,241, 6,060,569, 6,174,975, WO9842664 and WO9842665, all of which are incorporated by reference herein for all purposes as if fully set forth. Each type of polymerization catalyst has its advantages and disadvantages, and due the commercial importance of polyolefins, new polymerization catalysts are constantly being sought.
One aspect of the present invention concerns a first process for the polymerization of olefins, comprising the step of contacting, at a temperature of about xe2x88x92100xc2x0 C. to about +200xc2x0 C., one or more monomers selected from the group consisting of ethylene and an olefin of the formula H2Cxe2x95x90CH(CH2)nH (XXII), and a Cr, Mn, V, Ti, Zr or Hf complex of an anion of the formula (I) 
wherein:
R1 is hydrocarbyl or substituted hydrocarbyl, R2 is hydrogen, hydrocarbyl or substituted hydrocarbyl, and R3 is hydrogen, hydrocarbyl, substituted hydrocarbyl or a functional group, provided that R1 and R2 taken together may be orthoarylene or substituted ortho-arylene, or R1, R2 and R3 taken together may form one or more rings;
Z is a bridging group of the formula (II), (III) or (IV) 
Q is nitrogen, oxygen, phosphorous or sulfur, provided that when Z is (II), Q is oxygen;
R4 is hydrogen, hydrocarbyl or substituted hydrocarbyl, provided that when Q is oxygen or sulfur R4 is not present;
R6 is hydrogen, hydrocarbyl or substituted hydrocarbyl, provided that R3 and R6 together may form a ring;
R7is hydrogen, hydrocarbyl or substituted hydrocarbyl, provided that R3, R6 and R7 together may form an aromatic ring, or R6 and R7 taken together may form a ring;
R8 is hydrogen, hydrocarbyl or substituted hydrocarbyl;
R9 is hydrogen, hydrocarbyl or substituted hydrocarbyl, provided that R4 and R9 taken together may be part of a double bond to an imino nitrogen atom, or R8 and R9 taken together may form a carbonyl with the carbon to which they are attached, or R8 and R9 taken together may form a ring, or R4 and R9 taken together may form a ring, or R4, R8 and R9 taken together may form a ring, or R6, R7, R8 and R9 taken together may form an aromatic ring;
R10, R11, R12 and R13 are each independently hydrogen, hydrocarbyl or substituted hydrocarbyl, provided that R10, R11, R12 and R13 taken together may be ortho-arylene;
R14 and R15 are each independently hydrogen, hydrocarbyl or substituted hydrocarbyl, provided that R14 and R15 taken together may form a carbonyl with the carbon to which they are attached, or R12, R13, R14, and R15 taken together may form an o-arylene group, or R10, R11, R12, R13, R14, and R15 taken together may form a fused aromatic ring system, or R13 and R14 taken together may form a ring;
R20 and R21 are each independently hydrogen, hydrocarbyl or substituted hydrocarbyl, or R20 and R21 taken together may form a ring;
each R22 is individually hydrocarbyl, oxygen or alkoxy, provided that when R22 is oxygen, two of R22 are taken together to form Txe2x95x90O;
n is an integer of 1 or more;
T is phosphorous or sulfur whose oxidation state is 3 or greater; and
x is equal to the oxidation state of T minus 2.
Another aspect of the present invention concerns a second process for the polymerization of olefins, comprising the step of contacting, at a temperature of about xe2x88x92100xc2x0 C. to about +200xc2x0 C., one or more monomers selected from the group consisting of ethylene and H2Cxe2x95x90CH(CH2)nH (XXII), with a compound of the formula (V) 
wherein:
R1, R2, R3, R4, Q, Z (and all R groups associated with Z), M and m are as defined above for (I),
M is Ti, Zr, Hf, V, Mn or Cr;
m is an integer equal to the valence of M minus 2; and
each L1 is independently a monodentate monoanionic ligand and at least for one of L1 an ethylene molecule may insert between L1 and M, and L2 is a monodentate neutral ligand which may be displaced by ethylene or an empty coordination site, provided that an L1 and L2 taken together may be a monoanionic polydentate ligand and at least for one of these monoanionic polydentate ligands ethylene may insert between said monoanionic polydentate ligand and M.
In the above-mentioned processes, (V) and/or the transition metal complex of (I) may in and of themselves be active catalysts, or may be xe2x80x9cactivatedxe2x80x9d by contact with a co-catalyst/activator.
The present invention also concerns a compound of the formula (VI) 
wherein R1, R2, R3, R4, Q, Z (and all R groups associated with Z), M and m are as defined above for (IV),
is 0 or 1; and
each L3 is independently a monodentate monoanionic ligand, and L4 is a monodentate neutral ligand or an empty coordination site, provided that an L3 and L4 taken together may be a monoanionic bidentate ligand.
Further aspects of the present invention include, for example, the anion of the formula (I) as defined above, a Ti, Zr, Hf, V, Mn or Cr complex of such anion, and the combination of such complex, (V) and/or (VI) with a co-catalyst.
Herein, certain terms are used. Some of them are:
A xe2x80x9chydrocarbyl groupxe2x80x9d is a univalent group containing only carbon and hydrogen. As examples of hydrocarbyls may be mentioned unsubstituted alkyls, cycloalkyls and aryls. If not otherwise stated, it is preferred that hydrocarbyl groups herein contain 1 to about 30 carbon atoms.
By xe2x80x9csubstituted hydrocarbylxe2x80x9d herein is meant a hydrocarbyl group that contains one or more substituent groups which are inert under the process conditions to which the compound containing these groups is subjected (e.g., an inert functional group, see below). The substituent groups also do not substantially detrimentally interfere with the polymerization process or operation of the polymerization catalyst system. If not otherwise stated, it is preferred that substituted hydrocarbyl groups herein contain 1 to about 30 carbon atoms. Included in the meaning of xe2x80x9csubstitutedxe2x80x9d are chains or rings containing one or more heteroatoms, such as nitrogen, oxygen and/or sulfur, and the free valence of the substituted hydrocarbyl may be to the heteroatom. In a substituted hydrocarbyl, all of the hydrogens may be substituted, as in trifluoromethyl.
By xe2x80x9c(inert) functional groupxe2x80x9d herein is meant a group other than hydrocarbyl or) substituted hydrocarbyl that is inert under the process conditions to which the compound containing the group is subjected. The functional groups also do not substantially interfere with any process described herein that the compound in which they are present may take part in. Examples of functional groups include halo (fluoro, chloro, bromo and iodo), ether such as xe2x80x94OR23 wherein R23 is hydrocarbyl or substituted hydrocarbyl. In cases in which the functional group may be near a metal atom the functional group should not coordinate to the metal atom more strongly than the groups in those compounds are shown as coordinating to the metal atom, that is they should not displace the desired coordinating group.
By a xe2x80x9ccocatalystxe2x80x9d or xe2x80x9ccatalyst activatorxe2x80x9d is meant one or more compounds that react with a transition metal compound to form an activated (or more active) catalyst species. A preferred catalyst activator is an xe2x80x9calkyl aluminum compoundxe2x80x9d, that is, a compound which has at least one alkyl group bound to an aluminum atom. Other groups such as alkoxide, hydride, and halogen may also be bound to aluminum atoms in the compound.
By xe2x80x9cneutral Lewis basexe2x80x9d is meant a compound, which is not an ion, that can act as a Lewis base. Examples of such compounds include ethers, amines, sulfides and organic nitriles.
By xe2x80x9cneutral Lewis acidxe2x80x9d is meant a compound, which is not an ion, that can act as a Lewis acid. Examples of such compounds include boranes, alkylaluminum compounds, aluminum halides and antimony [V] halides.
By xe2x80x9ccationic Lewis acidxe2x80x9d is meant a cation that can act as a Lewis acid. Examples of such cations are sodium and silver cations.
By an xe2x80x9cempty coordination sitexe2x80x9d is meant a potential coordination site on a metal atom that does not have a ligand bound to it. Thus if an ethylene molecule is in the proximity of the empty coordination site, the ethylene molecule may coordinate to the metal atom.
By a xe2x80x9cligand into which an ethylene molecule may insertxe2x80x9d between the ligand and a metal atom, or a xe2x80x9cligand that may add to ethylenexe2x80x9d, is meant a ligand coordinated to the metal atom (which forms a bond Lxe2x80x94M) into which an ethylene molecule (or a coordinated ethylene molecule) may insert to start or continue a polymerization. For instance, this may take the form of the reaction (wherein L is a ligand): 
By a xe2x80x9cligand which may be displaced by ethylenexe2x80x9d is meant a ligand coordinated to a transition metal, which when exposed to ethylene is displaced as the ligand by the ethylene.
By a xe2x80x9cneutral ligandxe2x80x9d is meant a ligand that is not charged.
xe2x80x9cAlkyl groupxe2x80x9d and xe2x80x9csubstituted alkyl groupxe2x80x9d have their usual meaning (see above for substituted under substituted hydrocarbyl). Unless otherwise stated, alkyl groups and substituted alkyl groups preferably have 1 to about 30 carbon atoms.
By xe2x80x9carylxe2x80x9d is meant a monovalent aromatic group in which the free valence is to the carbon atom of an aromatic ring. An aryl may have one or more aromatic rings which may be fused, connected by single bonds or other groups.
By xe2x80x9csubstituted arylxe2x80x9d is meant a monovalent aromatic group substituted as set forth in the above definition of xe2x80x9csubstituted hydrocarbylxe2x80x9d. Similar to an aryl, a substituted aryl may have one or more aromatic rings which may be fused, connected by single bonds or other groups; however, when the substituted aryl has a heteroaromatic ring, the free valence in the substituted aryl group can be to a heteroatom (such as nitrogen) of the heteroaromatic ring instead of a carbon.
By a xe2x80x9cxcfx80-allyl groupxe2x80x9d is meant a monoanionic ligand with 1 sp3 and two adjacent sp2 carbon atoms bound to a metal center in a delocalized xcex73 fashion. The three carbon atoms may be substituted with other hydrocarbyl groups or functional groups.
By xe2x80x9cortho-arylenexe2x80x9d (or xe2x80x9co-arylenexe2x80x9d) is meant a divalent aryl group in which the free valencies are on adjacent carbon atoms. The o-arylene ring may be part of a fused and/or heterocyclic ring system and/or contain substituents such as hydrocarbyl groups or functional groups.
The polymerizations herein are carried out by a transition metal complex of anion (I). Many of the groups in (I) may have various forms, that is they may be xe2x80x9csimplexe2x80x9d groups such as hydrogen or alkyl, or they may participate in multiple bonds such as an imino bond to nitrogen or a carbon atom in an aromatic ring and/or they may be part of ring or ring systems. Some of these groups may optionally for instance be part of two different rings. Clearly simple valence rules are not broken in these anions and compounds, for example carbon will have a valence of 4. Thus if a particular group is part of one ring, it cannot be part of another ring or group that would violate these simple valence rules.
In order to illustrate this, and since (I) and its conjugate acid and transition metal complexes may have various individual structures, some of the conjugate acid structures are shown below, with certain salient features pointed out. 
In (VII), referring back to structure (I), R1 and R2 are taken together to form o-arylene (o-phenylene); R3 is R28; Z is (III); R6, R7, R8 and R9 are taken together to form an aromatic ring; and Q is oxygen. Generally in (VII), R24, R25, R26, R27, R29, R30, R31 and R32 are each independently hydrogen, hydrocarbyl, substituted hydrocarbyl or a functional group, and R28 is hydrogen, hydrocarbyl or substituted hydrocarbyl, provided that any two of R24, R25, R26, R27, R29, R30, R31 and R32 vicinal to one another may be taken together to form a ring, and that R27 and R28 may be taken together to form a ring, or R28 and R29 may be taken together to form a ring. 
In (VIII), R1 and R2 are taken together to form o-arylene (o-phenylene); R3 is hydrogen; Z is (III); R6 and R7 are hydrogen; R8 and R9 are trifluoromethyl; and Q is oxygen. 
In (IX), R1 and R2 are taken together to form o-arylene (o-phenylene); R3 is hydrogen; Z is (III); R6 and R7 are hydrogen; R8 and R9 are taken together to form a carbonyl with the carbon to which they are attached; and Q is oxygen. 
In (X), R1, R2 and R3 are taken together to form a fused ring system, Z is (III), R6, R7, R8 and R9 are taken together to form an aromatic ring, and Q is oxygen. 
In (XI), R1 are R2 are taken together to form o-arylene (o-phenylene); R3 is hydrogen; Z is (III); R6, R7, R8 and R9 are taken together to form an aromatic ring; and Q is sulfur. 
In (XII), R1 and R2 are taken together to form o-arylene (o-phenylene); R3 is hydrogen; Z is (II); R20 and R21 are hydrogen; x is 4; T is sulfur; two each (twice) of R22 are taken together to form Sxe2x95x90O; and Q is oxygen. 
In (XIII), R1 and R2 are taken together to form o-arylene (o-phenylene); R3 is hydrogen; Z is (II); R20 and R21 are hydrogen; x is 3; T is phosphorous; two of R22 are taken together to form Pxe2x95x90O; the other of R22 is alkoxy; and Q is oxygen. 
In (XIV), R1 and R2 are taken together to form o-arylene (o-phenylene); R3 is hydrogen; Z is (III); R6, R7 and R8 are hydrogen; R4 and R9 are taken together to form a ring; and Q is nitrogen. 
In (XV), R1 is trifluoromethyl; R2 is hydrogen; R3 is methyl; Z is (III); R6, R7, R8 and R9 are taken together to form an aromatic ring; and Q is oxygen. 
In (XVI), R1 and R2 are taken together to form o-arylene (o-phenylene); R3 is hydrogen; Z is (IV); R10, R11, R12 and R13 are taken together form o-arylene; R14 and R15 are taken together together form a carbonyl with the carbon to which they are attached; R4 is 2,6-di-iso-propylphenyl; and Q is nitrogen. 
In (XVII), R1 and R2 are taken together to form o-arylene (o-phenylene); R3 is hydrogen; Z is (III); R6 and R7 are hydrogen; R8 is methyl; R4 and R9 are taken together to form a ring; and Q is nitrogen. 
In (XVIII), R1 and R2 are taken together to form o-arylene (o-phenylene); R3 is hydrogen; Z is (III); R6, R7 and R8 are hydrogen; R4 and R9 are taken together to form a ring; and Q is nitrogen. 
In (XIX), R1 and R2 are taken together to form o-arylene (o-phenylene); R3 is hydrogen; Z is (IV); R10, R11, R12 and R13 are taken together to form o-arylene; R14 and R15 are taken together to form a carbonyl with the carbon to which they are attached; and Q is oxygen. 
In (XX), R1 and R2 are taken together to form o-arylene (o-phenylene); R3 is hydrogen; Z is (IV); R10, R11, R12, R13, R14 and R15 are taken together to form a fused aromatic ring system; and Q is oxygen. 
In (XXI), R1 and R2 are taken together to form o-arylene (o-phenylene); R3 is hydrogen; Z is (IV); R10 and R11 are hydrogen; R12, R13, R14 and R15 are taken together to form an o-arylene group; and Q is oxygen.
In all of compounds (VII) through (XXI), groups and/or substituents may be changed where appropriate, for example methyl groups may be changed to other hydrocarbyl groups or hydrogen, hydrogen may be change to hydrocarbyl or functional groups.
A preferred anion (I), and all of its conjugate acid and metal complexes, is (VII), which is shown in the conjugate acid form. In its anion form, (VII) can be represented by the formula (XXVI) 
In its metal complex form, (VII) can be represented by the formulas (XXVII) and (XXVIII) 
In (VII), (XXVI), (XXVII) and (XXVIII), it is preferred that:
any or all of R24 through R32 are hydrogen; and/or
R24 and R26 are nitro; and/or
R24 and R26 are alkyls containing 1 to 6 carbon atoms, especially t-butyl;
R29 is an alkyl containing 1 to 6 carbon atoms, especially methyl; and/or
R26 and R27 taken together form an aromatic ring, especially a 6-membered carbocylic aromatic ring.
In preferred specific compounds of (VII), (XXVI), (XXVII) and (XXVIII), R25, R27, R28, R30, R31 and R32 are hydrogen, R29 is methyl, and R24 and R26 are nitro; or R25, R27, R28, R30, R31 and R32 are hydrogen, R29 is methyl, and R24 and R26 are t-butyl; or R24, R25, R28, R30, R31 and R32 are hydrogen, R29 is methyl, and R26 and R27taken together form a 6-membered carbocyclic aromatic ring.
The structure illustrated by (I) is not meant to preclude other tautomers, and all such tautomers are included herein. For instance such structures (partial structures shown) may include: 
The conjugate acids of (I) can be made by a variety of methods, most of which are familiar to the skilled organic synthetic chemist, and which method(s) are chosen will depend on the particular structure desired, such as (VII) through (XXI). In all instances, if certain substituents/substitution patterns are desired, starting materials with those substituents/substitution patterns may be used. For example, (VII) may be made by reacting an appropriate salicylaldehyde with an appropriate 2-hydroxy-2-aminomethylpyridine. (VIII) may be made by reacting salicylaldehyde with 3,3,3-trifluoro-2-hydroxy-2-trifluoromethylpropylamine. (IX) can be made by reacting aminoacetic acid with salicylaldehyde. (X) can be made by reacting salicylaldehyde with 5-hydroxy-1,4-naphthalenedione. (XI) may be made by salicylaldehyde with 2-thioaniline. (XII) may be made by reacting salicylaldehyde with methyl aminomethyl sulfonate and hydrolyzing the resulting sulfonic ester-imine to the sulfonic acid-imine. (XIII) may be made by reacting salicylaldehyde with dimethyl aminomethyl phosphite and hydrolyzing the resulting phosphite diester-imine to the phosphite ester-acid-imine. (XIV) may be made by reacting salicylaldehyde with 4-aminomethyl-3-pyrrolin-2-one. (XV) may be made by reacting 1,1,1-trifluoro-2,5-pentanedione with 2-hydroxyaniline. (XVI) can be made by reacting o-aminobenzoic acid with salicylaldehyde, converting the resulting iminocarboxylic acid to the acyl halide and reacting the acyl halide with 2,6-diisopropylaniline. Some of these types of syntheses are also given in the Examples.
(I), the anion of the above conjugate acids, can be prepared by reaction of the conjugate acid with a strong base, such as an alkali metal hydride, an alkali metal alkoxide or a lithium disilylamide. It is preferred at this point that the cation(s) to this anion is an alkali metal cation, such as lithium, sodium and potassium. (I) may isolated as a salt and then used to form the transition metal compound, or may be formed and used in situ to produce the transition metal compound. The transition metal compound of (I) may be prepared by reacting (I) with an appropriate compound of the transition metal. For early transition metals such as Zr and Ti, the transition metal compound may be a halide such as TiCl4 or ZrCl4, in which case the ligands other than (I) attached to the metal will be halide such as chloride.
If (VI) is not already equivalent to (V), it may be converted to (V) before or during the polymerization process by reaction with other appropriate compounds (such as cocatalysts). Alternatively, the conjugate acid of (I) can be reacted with a transition metal compound such as TiCl4, TiCl4.2THF or ZrCl4 in the presence of a base to neutralize the liberated hydrohalic acid.
In some of the structures written herein, such as (V) and (VI), it is not meant that (I) is a tridentate ligand, although it may be. The structures are written as they are for convenience, and to show that the anionic ligands (I) could be tridentate, but they may be only bidentate or even monodentate. Although it is believed in theory the ligands can be tridentate, the Applicants do not wish to be bound by this theory.
As implied above, (I) will normally be associated with a positively charged species, such as a cation. This may be a transition metal cation (as in (V)), or may be another cation such as an alkali metal cation.
In (V) useful groups L1 include halide (especially chloride), hydrocarbyl and substituted hydrocarbyl (especially phenyl and alkyl, and particularly phenyl, methyl, hydride and acyl). Useful groups for L2 include phosphine such as triphenylphosphine, nitrile such as acetonitrile, ethers such as ethyl ether, pyridine, and tertiary alkylamines such as triethylamine and TMEDA (N,N,Nxe2x80x2,Nxe2x80x2-tetramethyl-1,2-ethylenediamine). Alternatively L1 and L2 taken together may be a xcfx80-allyl or xcfx80-benzyl group such as 
wherein R is hydrocarbyl, and xcfx80-allyl and xcfx80-benzyl groups are preferred.
In another variation, L3 and L4 taken together may be a xcex2-diketonate ligand. If this ligand is present in (VI), it may be converted to (V) by use of a suitable alkylating agent such as an alkylaluminum compound, Grignard reagent or alkyllithium compound.
In (V) when ethylene may insert between L1 and the transition metal atom, and L2 is an empty coordination site or is a ligand which may be displaced by ethylene, or L1 and L2 taken together are a bidentate monoanionic ligand into which ethylene may be inserted between that ligand and the transition metal atom, (V) may by itself catalyze the polymerization of an olefin. Examples of L1 which form bonds with the transition metal into which ethylene may insert are hydrocarbyl and substituted hydrocarbyl, especially phenyl and alkyl, and particularly methyl, hydride and acyl. Ligands L2 which ethylene may displace include phosphine such as triphenylphosphine, nitrile such as acetonitrile, ether such as ethyl ether, pyridine, tertiary alkylamines such as TMEDA, and other olefins such as ethylene or isobutylene. Ligands in which L1 and L2 taken together are a monoanionic polydentate ligand into which ethylene may insert between that ligand and the transition metal atom include xcfx80-allyl- or xcfx80-benzyl-type ligands (in this instance, sometimes it may be necessary to add a neutral Lewis acid cocatalyst such as triphenylborane to initiate the polymerization, see for instance previously incorporated U.S. Pat. No. 6,174,975). For a summary of which ligands ethylene may insert into (between the ligand and transition metal atom) see, for instance, J. P. Collman, et al., Principles and Applications of Organotransition Metal Chemistry, University Science Book, Mill Valley, Calif., 1987, included herein by reference. If for instance L1 is not a ligand into which ethylene may insert between it an the transition metal atom, it may be possible to add a co-catalyst which may convert L1 into a ligand which will undergo such an insertion. Thus if L1 is halo such as chloride or bromide, or carboxylate, it may be converted to hydrocarbyl such as alkyl by use of a suitable alkylating agent such as an alkylaluminum compound, a Grignard reagent or an alkyllithium compound. It may be converted to hydride by use of a compound such as sodium borohydride.
As indicated above, when L1 and L2 taken together are a monoanionic polydentate ligand, a cocatalyst (sometimes also called an activator) which is an alkylating or hydriding agent is also typically present in the olefin polymerization. A preferred cocatalyst is an alkylaluminum compound, and useful alkylaluminum compounds include trialkylaluminum compounds such as triethylaluminum, trimethylaluminum and tri-iso-butylaluminum, alkyl aluminum halides such as diethylaluminum chloride and ethylaluminum dichloride, and aluminoxanes such as methylaluminoxane. More than one such co-catalyst may be used in combination.
In (VI) in one preferred form at least one of L3 is a ligand into which ethylene may insert between L3 and the transition metal atom, and L4 is an empty coordination site or a ligand which may be displaced by ethylene. In another preferred form of (VI), each of L3 is a ligand into which ethylene may not insert between that ligand and the transition metal atom, such as halide, especially chloride, and carboxylate.
In the transition metal complexes of the present invention preferred metals are Ti and Zr. Generally speaking early transition metal complexes such as Ti and Zr produce polymers with the xe2x80x9cexpectedxe2x80x9d number and length of branches (see previously incorporated U.S. Pat. No. 5,880,241 for an explanation of xe2x80x9cexpectedxe2x80x9d branching). For example homopolyethylene will have essentially no branching (after correcting for end groups), while poly(1-hexene) will have an n-butyl branch every other carbon atom (on average) of the main polymer chain.
A preferred olefin is ethylene, and when olefins other than ethylene are polymerized, it is preferred that they be copolymers with ethylene. In other preferred olefins n is 1 to 20.
In the polymerization processes herein, the temperature at which the polymerization is carried out is about xe2x88x92100xc2x0 C. to about +200xc2x0 C., preferably about xe2x88x9260xc2x0 C. to about 150xc2x0 C., more preferably about xe2x88x9220xc2x0 C. to about 100xc2x0 C. The pressure of the olefin (if it is a gas) at which the polymerization is carried out is not critical, atmospheric pressure to about 275 MPa being a suitable range.
The polymerization processes herein may be run in the presence of various liquids, particularly aprotic organic liquids. The catalyst system, monomer(s) and/or polymer may be soluble or insoluble in these liquids, but obviously these liquids should not prevent the polymerization from occurring. Suitable liquids include alkanes, cycloalkanes, selected halogenated hydrocarbons and aromatic hydrocarbons. Specific useful solvents include hexane, toluene, benzene methylene chloride, and 1,2,4-trichlorobenzene.
The olefin polymerizations herein may also initially be carried out in the xe2x80x9csolid statexe2x80x9d by, for instance, supporting the transition metal compound on a substrate such as silica or alumina, activating it if necessary with one or more cocatalysts and contacting it with the olefin(s). Alternatively, the support may first be contacted (reacted) with one or more cocatalysts (if needed) such as an alkylaluminum compound, and then contacted with an appropriate transition metal compound. The support may also be able to take the place of a Lewis or Bronsted acid, for instance an acidic clay such as montmorillonite, if needed. These xe2x80x9cheterogeneousxe2x80x9d catalysts may be used to catalyze polymerization in the gas phase or the liquid phase. By gas phase is meant that a gaseous olefin is transported to contact with the catalyst particle.
In all of the polymerization processes described herein oligomers and polymers of the various olefins are made. They may range in molecular weight from oligomeric POs (polyolefins), to lower molecular weight oils and waxes, to higher molecular weight POs. One preferred product is a polymer with a degree of polymerization (DP) of about 10 or more, preferably about 40 or more. By xe2x80x9cDPxe2x80x9d is meant the average number of repeat (monomer) units in a polymer molecule.
Depending on their properties, the polymers made by the processes described herein are useful in many ways. For instance if they are thermoplastics, they may be used as molding resins, for extrusion, films, etc. If they are elastomeric, they may be used as elastomers. See for instance previously incorporated U.S. Pat. No. 5,880,241.
Depending on the process conditions used and the polymerization catalyst system chosen, polymers, even those made from the same monomer(s) may have varying properties. Some of the properties that may change are molecular weight and molecular weight distribution.
It is known that blends of distinct polymers, that vary for instance in the properties listed above, may have advantageous properties compared to xe2x80x9csinglexe2x80x9d polymers. For instance it is known that polymers with broad or bimodal molecular weight distributions may be melt processed (be shaped) more easily than narrower molecular weight distribution polymers. Thermoplastics such as crystalline polymers may often be toughened by blending with elastomeric polymers.
Therefore, methods of producing polymers that inherently produce polymer blends are useful especially if a later separate (and expensive) polymer mixing step can be avoided. However in such polymerizations one should be aware that two different catalysts may interfere with one another, or interact in such a way as to give a single polymer.
In such a process the transition metal containing polymerization catalyst disclosed herein can be termed the first active polymerization catalyst. Monomers useful with these catalysts are those described (and also preferred) above. A second active polymerization catalyst (and optionally one or more others) is used in conjunction with the first active polymerization catalyst. The second active polymerization catalyst may be a transition metal catalyst, for example as described in previously incorporated U.S. Pat. Nos. 5,714,556, 5,880,241, 6,060,569 and 6174975, as well as 5,955,555 which is also incorporated by reference herein for all purposes as if fully set forth.
Other useful types of catalysts may also be used for the second active polymerization catalyst. For instance so-called Ziegler-Natta and/or metallocene-type catalysts may also be used. These types of catalysts are well known in the polyolefin field, see for instance Angew. Chem., Int. Ed. Engl., vol. 34, p. 1143-1170 (1995), EP-A-0416815 and U.S. Pat. No. 5,198,401 for information about metallocene-type catalysts, and J. Boor Jr., Ziegler-Natta Catalysts and Polymerizations, Academic Press, New York, 1979 for information about Ziegler-Natta-type catalysts, all of which are hereby included by reference. Many of the useful polymerization conditions for all of these types of catalysts and the first active polymerization catalysts coincide, so conditions for the polymerizations with first and second active polymerization catalysts are easily accessible. Oftentimes the xe2x80x9cco-catalystxe2x80x9d or xe2x80x9cactivatorxe2x80x9d is needed for metallocene or Ziegler-Natta-type polymerizations. In many instances the same compound, such as an alkylaluminum compound, may be used as an xe2x80x9cactivatorxe2x80x9d for some or all of these various polymerization catalysts.
In one preferred process described herein the first olefin(s) (olefin(s) polymerized by the first active polymerization catalyst) and second olefin(s) (the monomer(s) polymerized by the second active polymerization catalyst) are identical. The second olefin may also be a single olefin or a mixture of olefins to make a copolymer.
In some processes herein the first active polymerization catalyst may polymerize a monomer that may not be polymerized by said second active polymerization catalyst, and/or vice versa. In that instance two chemically distinct polymers may be produced. In another scenario two monomers would be present, with one polymerization catalyst producing a copolymer, and the other polymerization catalyst producing a homopolymer.
Likewise, conditions for such polymerizations, using catalysts of the second active polymerization type, will also be found in the appropriate above mentioned references.
Two chemically different active polymerization catalysts are used in this polymerization process. The first active polymerization catalyst is described in detail above. The second active polymerization catalyst may also meet the limitations of the first active polymerization catalyst, but must be chemically distinct. For instance, it may utilize a different ligand that differs in structure between the first and second active polymerization catalysts. In one preferred process, the ligand type and the metal are the same, but the ligands differ in their substituents.
Included within the definition of two active polymerization catalysts are systems in which a single polymerization catalyst is added together with another ligand, preferably the same type of ligand, which can displace the original ligand coordinated to the metal of the original active polymerization catalyst, to produce in situ two different polymerization catalysts.
The molar ratio of the first active polymerization catalyst to the second active polymerization catalyst used will depend on the ratio of polymer from each catalyst desired, and the relative rate of polymerization of each catalyst under the process conditions. For instance, if one wanted to prepare a xe2x80x9ctoughenedxe2x80x9d thermoplastic polyethylene that contained 80% crystalline polyethylene and 20% rubbery polyethylene, and the rates of polymerization of the two catalysts were equal, then one would use a 4:1 molar ratio of the catalyst that gave crystalline polyethylene to the catalyst that gave rubbery polyethylene. More than two active polymerization catalysts may also be used if the desired product is to contain more than two different types of polymer.
The polymers made by the first active polymerization catalyst and the second active polymerization catalyst may be made in sequence, i.e., a polymerization with one (either first or second) of the catalysts followed by a polymerization with the other catalyst, as by using two polymerization vessels in series. However it is preferred to carry out the polymerization using the first and second active polymerization catalysts in the same vessel(s), i.e., simultaneously. This is possible because in most instances the first and second active polymerization catalysts are compatible with each other, and they produce their distinctive polymers in the other catalyst""s presence. Any of the processes applicable to the individual catalysts may be used in this polymerization process with 2 or more catalysts, i.e., gas phase, liquid phase, continuous, etc.
The polymers produced by this two catalyst process may vary in molecular weight and/or molecular weight distribution and/or melting point and/or level of crystallinity, and/or glass transition temperature and/or other factors. The polymers produced are useful as molding and extrusion resins and in films as for packaging. They may have advantages such as improved melt processing, toughness and improved low temperature properties.
Catalyst components which include transition metal complexes of (I), with or without other materials such as one or more cocatalysts and/or other polymerization catalysts are also disclosed herein. For example, such a catalyst component could include the transition metal complex supported on a support such as alumina, silica, a polymer, magnesium chloride, sodium chloride, etc., with or without other components being present. It may simply be a solution of the complex, or a slurry of the complex in a liquid, with or without a support being present.
In the Examples, all pressures are gauge pressures. Branching was determined by 1H NMR, taking the total of the methyl carbon atoms as the number of branches. Branching is uncorrected for end groups. Some of the transition metal complexes may have one or more molecules of THF coordinated per molecule of complex.
In the Examples, the following abbreviations are used:
xcex94Hxe2x80x94heat of fusion
Mnxe2x80x94number average molecular weight
Mwxe2x80x94weight average molecular weight
PExe2x80x94polyethylene
PMAOxe2x80x94methylaluminoxane in toluene, 15.5 wt. % Al, from Akzo Chemicals, Inc.
RTxe2x80x94room temperature
THFxe2x80x94tetrahydrofuran
Tmxe2x80x94melting point by differential scanning calorimetry, taken as the peak of the melting endotherm at a heating rate of 10xc2x0 C./min.